Multi-power supply system design is now the main trend. Such designs use many voltage sources integrated into a single Multi-power supply system. Therefore, a single power supply can simultaneously supply different voltages to different function circuits. For example, when a function circuit of an apparatus needs a low voltage level to work, the low voltage power source on the multi-power power supply is connected to the function circuit by the multi-power supply system. On the other hand, when another function circuit of the apparatus needs a high voltage level to work, the low voltage power source on the multi-power power supply is connected to the function circuit. Therefore, the Multi-power power supply system can provide different voltage levels to different function circuits based on their work requirement, which can reduce power consumption.
However, to prevent different voltage sources from being simultaneously connected to the same circuit, the timing to turn on and turn off the voltage sources is very important. Typically, an application-specific integrated circuit (ASIC) controls the circuit. However, the ASIC is very expensive, which makes reducing the producing cost difficult. Therefore, an apparatus that can reduce the manufacturing cost and realize the timing control is needed.